RE: Script? did I hear script?
For those of you who can't wait to the end of my message, the conclusion is: "Making the scripting security to depend only on the file transfer accept/decline is still very risky."
Consider the following: Think of MSN (or Windows) Messenger as scriptable, speaking of what Patchou and other software writers do to extend Messenger's capabilities. Having said this, now think of all the worms that use Messenger as a spreading platform. People without the knowledge we have regarding Messenger accepts files and execute them without thinking twice. Please keep this in mind while reading my message.
Also, remember all the problems that scriptable mIRC clients imply, and also what happened when Office (Word, Excel...) applications started accepting programmable macros. Let's not make the same mistake.
Now, let's get back to MP2. Imagine an event like "OnAfterFileTransfer" which executes the file. If I write a small trojan .EXE which installs an MP2 script which secretly works in that event, executing any received file, I will no longer be able to receive files safely without executing them. Subsequent incoming files could be other worms which, would autoexecute themselves, which would turn this into a disease.
If the scripting includes an "OnStartup" event and allows the scripts to modify Messenger Plus! configuration, it is very easy to hide a worm and execute it each time Messenger (or MsgPlus) runs, reenabling worms frequently.
The last example almost speaks for itself: an "OnBeforeFileTransfer" which has been hooked to auto-receive files. Imagine it working together with the scenario I wrote for the hypotetical OnAfterFileTransfer.
This are the three most critical points I'm worried about. There are several other possible exploit points out there in any scripting environment. I would not like to see a worm named "worm.E@mmp2" (referring to Messenger Plus) or something like that.
Blaming a user who (typically) doesn't know or care about worms for accepting a file and executing it, will only be the defense against the already created disease. My different initial proposals to avoid these potential situations are:
1. Pesimistic: Not to have these kind of events planned.
2. Optimistic: To ignore this issues.
3. A somewhat better option ;) -- When calling OnBeforeFileTransfer and OnAfterFileTransfer, not to pass the received file name. Also, to have a special special .INI file in the Plus directory, or a RegistryKey for MP2 which, before any script processing, controls wether scripting (or part of it) should be enabled or disabled, so you can recover your Messenger sessions quickly in case of an infection.
Does anybody know if, using the proposed platform by Patchou, srcipts would be able to become resident after Messenger and Messenger Plus shuts down? I'm asuming they aren't able to.
Octavio.
This post was edited on 01-15-2003 at 11:19 AM by alvarezp.
|